The rotary motor may provide a driving power which can be converted to a planar movement by a mechanism. The mechanism is usually complex and the precision and speed of its transmission are limited for this, which is disadvantageous along with other problems such as frequent calibration, high cost, poor reliability and too big size. The early planar motor is operated by two planar type motors which are directly driven, which structure increases the complexity of the transmission system. In contrast, the planar motor, which can directly utilize electro-magnetic energy to drive the planar movement, has advantages of high concentration of force, low dissipation of heat and high precision etc, thus the inter-mediate transmitting device is saved which was used for converting a rotary movement into a planar movement and into another planar movement. And it becomes possible to integrate the object being controlled with the motor which has advantages such as quick response, good sensitivity, good servo control and simple structure.
Signal subdivision has a wide applicability in the fields of machinery and electronics. The magnetic field signals of the planar motor are distributed periodically, and when the signal varies in the one period, a fixed spatial displacement occurs correspondingly. Usually, the measurement circuit performs the measurement for the displacement by counting periods of the signal. When only counting the periods is performed, apparently, the resolution is the displacement corresponding to the one period of the signal. Thus, in order to improve the resolution of the instrument, subdivision must be required.